We are participating in a double blind therapeutic trial of cholesterol-lowering drugs, clofibrate, nicotinic acid, dextrothyroxine and premarin. We have 153 volunteers in Hawaii as a part of a national group of 8346 men aged 30-64, each having had at least one myocardial infarction. All men in the study are to be followed for at least 5 years. Data from 53 clinics are being sent to a coordinating center at the University of Maryland, responsible for its assembly, evaluation and statistical analysis.